Percussive tool



G. H. FUEHRER Feb. 1l, 1,941;

PERCUSSIVE TOOL Filed Dec.

Patented Feb. 11, 1941 UNITED STATES.

PATENT oFFicE v2,231,496 v PERCUSSIVE TOOL Application December 1, 1938,Serial-No. 243,368

5 Claims.

This invention relates to percussve tools, and more particularly to apercussive tool of the type that is held to the work and guided by theoperator.

One object of the invention is to make possible a nice control of thevalve mechanism effecting the distribution of pressure fluid to thepercussive element of the tool.

Other objects will be in part obvious and in part pointed outhereinafter. v

In the drawing accompanying this specification and in which similarreference numerals refer to similar parts- Figure 1 is a longitudinalView, partly in section, of a percussive tool constructed in accordancewith the practice of the invention and showing the pressure fluidcontrolling and distributing devices in operative positions,

Figure 2A is a view similar to Figure 1 showing the pressure iiuidcontrolling and distributing devices in the positions which they willoccupy during the time the percussive tool is idle, and

Figure 3 is a transverse View taken through Figure 1 on the line 3 3.

Referring more particularly to the drawing, the percussive tool,designated in general by 20, comprises a cylinder 2| havingl a forwardlyreduced extension 22 which is provided with external threads 23 forengagement with threads 24 of a front head 25 forming the foremostcasing portion of the tool.

The interior of the cylinder 2|! constitutes a piston chamber 26 and ahammer piston 21 is reciprocable in the piston chamber 26 to deliverblows to the shank 28 of a working implement 29 extending into the fronthead 25. An exhaust port 30, in an intermediate portion of the cylinder2|, is controlled by the piston 21 and in the outer surface of thecylinder 2| is an annular groove 3| to accommodate a muffler in the formof a split sleeve 32 for damping the noise of the exhaust uid issuingfrom the exhaust port 30.

In the front end of the cylinder 2| is a bushing 33 to guide the shank28 of the Working implement, and on the forward end of the bushing is anexternal flange 34 which is clamped between the end of the cylinder anda shoulder 35 in the front head to secure the bushing 33 in position.The bushing 33 serves as a stop for a collar 3S on the workingimplement, and in the forward extremity of the front head is a bushing31 to serve as a guide for a portion of the working implement lyingforwardly of the collar 36.

The rearward end of the piston chamber 26 is closed by a wall 38 whichis an integral portion of the cylinder, vand. `at diametrically oppositesides of the wall 38 and integraltherewith and with the cylinder 2| arelegs 39 and 40 which are joined by a bar 4| to serve as a grip memberfor the operators hand.

In accordance-with the practice of the invention, the leg 40 iskprovided With a bore 42 that extends into an enlargement 43 on the sideof the cylinder 2| to accommodate the valve mechanism whereby fluiddistribution to the piston chamber 26 is controlled. The valve mechanismcomprises a Valve chest 44 in the form of a plug which may be pressfitted or otherwise suitably secured in the bore 42.` The plug 44extends with its rearmost end into the plane of the bar 4| and isboredinvits forward portion to forma valve chamber 45-which is closed atits front end by a` plug 46 seating against the bottom of the bore 42.In the rearward end of the valve chamber 45 is a valve 41 whichreciprocates in the valve chamber to distribute pressure nui-d to thepiston chamber 26. 'I'he valve 41 is of the spool type having a pair ofend flanges 48 and 49 and a stem 50 connecting theflanges. The flanges48 and 49 are of the same-diameter. Their outer end surfaces constitute4pressure areas 5| and 52, respectively, against which air compressed bythe piston 21 acts to actuate the valve and such oompressed air is.carried to the surfaces 5| and 52 by passages 53 and 54, respectively,which also serve tov conveypressure fluid from the valve chamber to theends of the piston chamber.

A recess 55'in the plug 44, forming a continuation of the passage 54,opens into the rearward end of the valve chamber 45, and at the junctureof the recess 55 with the valve chamber 45 is a shoulder 56 that-Servesas a valve stop or seat which the flange 49 engages to limittherearward. travel of the valve.

The pressurefluid distributed by the valve 4-1 enters` the valve chamber45 through a supply passage51l in the transverse plane of the spacebetween the anges 48 and 49'and passes over the peripheral surfaces ofthe iianges to the passages 53 and 54. Annular grooves 58 and 59encircling the anges 48 and 49 provide the spaces necessary around thevalve flanges for the pressure fluid flowing to the inlet passages.

Suitable means are provided to enable the movement of the valve 41 to becontrolled with the hand grasping the bar or grip member 4|. To thisen-d a plunger 6|) is disposed in the front end of the valve chamber 45to act as a movable stop member for the valve. The plunger 60 is freelyslidable in the valve chamber. Its rearward end surface 6| acts as aseat for the actuating surface 5l of the valve and in the plunger are aseries of longitudinally extending passages 62 that open into an annulargroove 63 adapted to register with the inlet passage 53.

During the inoperative period of the percussive tool the plunger 60 isheld against the Valve 41 and the valve, in turn, is held against theshoulder 56 by a spring E4 arranged in the plug 46 and seating againstthe plunger. The opposite end of the plunger carries a stem 65 thatextends sli-dably through the valve 41, to guide the valve, and therearmost or free end 66 of the stem extends into a groove 61 in the gripmember 4I to receive the thrust of a lever 68 mounted pivotally in thegroove 61 on a pin 59.

In practice, and during the idle or non-operating position of the parts,the spring 64 presses the plunger 6U against the actuating surface-5land maintains the actuating surface 52 seated against the shoulder 55,thus preventing admission of pressure fluid to either of the inletpassages 53 and 54. Y

Whenever it is desired to set the piston 21 in motion for actuating thewo-rking implement 29 the plunger 65 is depressed by pressure appliedagainst the lever 68. In this way the valve 41 is released and will thenreciprocate to distribute the pressure fluid to the inlet passages 53and 54. More specically, in the position of the valve shown in Figure 1,pressure fluid ows from the supply passage 51 over the flange 49 andthrough the recess 55 and the inlet passage 54 into the rearward end ofthepiston chamber to drive the piston 21 forwardly on its workingstroke.

After the piston 21 reaches a position in which it covers the exhaustport 35 the air in 1the front end of the piston chamber will becompressed and forced through the passages 53, 63 and 62 against theactuating surface 5l and shift the valve rearwardly against the shoulder56 t-o cut-off the admission of pressure fluid to the rearward end ofthe piston chamber. In the new position of the valve pressure uid flowsover the valve flange 48 through the passages 62 and associated channelsinto the front end of the piston chamber to return the piston.

When, during its rearward stroke, Ithe piston covers the exhaust port 30the ail` in the rearward end of the piston chamber 26 will be compressedand forced through the passage 54 and the recess 55 against theactuating surface 52 and return the valve 41 to its initial position.

I claim:

1. In a fluid actuated percussive tool, the combination of a casinghaving a piston chamber and a piston in the piston chamber, a v-alvechest having a valve chamber, inlet passages leading from the valvechamber to the piston chamber, a valve in the valve chamber to valvepressure fluid from supply to the inlet passages, a stationary stopmeans coooperating with the valve to prevent admission of pressure fluidto one inlet passage, and

a stop member in the valve chamber movable automatically in onedirection for holding the valve against the stop means and to cooperatewith the valve -to prevent the admission of pressure fluid into anotherinlet passage.

2. In a uid actuated percussive tool, the combination `of a casinghaving a piston chamber and a piston in the piston chamber, a valvechest having a valve chamber, inlet passages leading from the valvechamber to the piston chamber, a valve reciprocable in the valve chamberto valve pressure fluid from supply to the inlet passages, a stationarystop means cooperating with the valve to prevent admission of pressurefluid to one inlet passage, a stop member in the valve chamber movableautomatically in one direction for holding the valve against the stopmeans and cooperating with the valve `to prevent the admission ofpressure uid into another inlet passage, means for manually moving thestop member in an opposite direction, and means on the stop member toguide the valve.

3. In a fluid actuated percussive tool, the combination of a casinghaving a piston chamber and a piste-n in the piston chamber, a valvechest having a valve chamber, inlet passages leading from the valvechamber to the pist-on chamber, a valve reciprocable in the valvechamber to valve pressure fluid from supply to the inlet passages, astationary stop means in the valve chest cooperating with an end of thevalve to prevent admission `of pressure fluid to one inlet passage, amanually movable spring-pressed stop member for controlling the movementof the valve, and a stem on the stop member extending through the valvefor guiding said valve.

4. In a fluid actuated percussive tool, the combination of a casinghaving a piston chamber and a piston in the piston chamber, a valvechest having a valve chamber, inlet passages leading from the valvechamber to the piston chamber, a valve in the valve chamber to effectthe distribution of pressure uid to the inlet passages, manuallyoperable spring-pressed means in the valve chamber for controlling themovement of the valve, and means on said manually operable means forguiding the valve.

5. In a fluid actuated percussive tool, the combination of a casinghaving a piston chamber and a piston in the piston chamber, a valvechest having a Valve chamber, inlet passages leading from the valvechamber to the piston chamber, ya reciprocatory valve in the valvechamber for controlling the distribution of pressure fluid to the inletpassages,l a manually operable springpressed plunger in the valvechamber to control the movement of the valve and having a passage toconvey pressure fluid from the valve chamber to an inlet passage, a rodon the plunger extending through the valve to form a guide therefor, andmanually operable means for shifting the plunger to a limiting position.

GEORG-E H. FUEHRER.

